Does anyone know how hot a rolling boil is?!
it's the same temp. rolling boil simply means that all the water in the pot is boiling and it is about to boil over. water can never be heated above 212 unless in a pressurized container.
Same temperature. Water can't actually become hotter than its boiling point without becoming steam. So a rolling boil is 212 degrees Fahrenheit. But it's "rolling" because all of the water molecules have hit their Brownian limit, so you can't "stir it down" and calm the activity without actually removing the heat source.
that is the boiling temperature at sea level and varies with elevation when water breaks bubbles at surface it should gather momentum to the rolling boil when covered within seconds. Other liquids such as candy making will best be judged with a candy thermometer as to cooking stage